Microbial, chemical, textural and sensory properties of coated rainbow trout by chitosan combined with pomegranate peel extract during frozen storage

Polycaprolactone (PCL)-based films integrated with hairy cellulose nanocrystals and silver nanoparticles for active Tilapia packaging applications

The migration of metal ions to the food matrix has been always a challenge in the production of active food packaging films. In this study, it was tried to evaluate the idea of using hairy cellulose nanocrystals (HCNs) in controlling the migration of Silver Nanoparticles (AgNPs) from polycaprolactone (PCL)-based films to the Tilapia fish. HCNs and the final films (integrated with various amounts of HCNs and AgNPs) were evaluated physicochemically and mechanically. Tilapia fish were packed using the films and after specific periods, the fish samples were assessed microbiologically and physiochemically. According to the results, incorporating NPs into PCL films enhanced tensile strength, elasticity, and toughness making the films more resistant to breakage and deformation under stress. The introduction of HCNs reduced the surface roughness level, decreasing AgNPs migration, but also accelerated the degradation rate. Films with [1% AgNPs +2% HCNs] and [1% AgNPs] had the lowest and highest water vapor transmission rate. The use of AgNPs (1%) + HCNs (2%) incorporated into PCL films resulted in a lower pH value, TVB-N, TBARs, and PV. It also decreased microbial activities in samples in comparison to the control. Therefore, the idea of using HCNs along with antibacterial metal-based nanoparticles can control the rate of ion migration.

Impact of frozen storage on physicochemical parameters and quality changes in cooked crayfish

Customers are increasingly opting for ready-to-eat and easy-to-prepare food products, such as cooked crayfish. It is highly valued for its unique taste, tender meat, and nutritional properties. Therefore, we conducted an investigation into its quality parameters over an 8-week period at -20 °C. Parameters such as water distribution, oxidation reactions, color, microstructure, texture properties, and physicochemical parameters were examined. The physicochemical results indicated that as the storage time increased, the levels of pH and TVB-N (total volatile basic nitrogen) showed a significant increase, while the water holding capacity decreased significantly (P < 0.05). After two months of frozen storage, the carbonyl content and TBARS (thiobarbituric acid reactive substances) increased to 4.15 ± 0.16 nmol/mg protein and 1.6 ± 0.00 mg/kg, respectively. Additionally, the total sulfhydryl content decreased to 4.91 ± 0.10 mol/105 g protein, which had an impact on the quality of the crayfish. Electron microscopy revealed that with increasing storage time, the fiber structure gradually deteriorated due to water crystallization, leading to severe damage and breakage of muscle fibers. Interestingly, these changes related to storage affected color and texture parameters, thereby influencing the overall quality of the crayfish.

The influence of γ-PGA on the quality of cooked frozen crayfish during temperature fluctuations

The purpose of this study was to compare the influences of gamma-poly glutamic acid (γ-PGA) (1, 2, 3, and 4 %) to see which could outperform conventional cryoprotectant mixture (4 % sorbitol + 4 % sucrose) on cooked crayfish properties, such as physicochemical, textural qualities, oxidation reaction, water distributions, and microstructure integrity, during different freeze-thaw cycles. Crayfish quality characteristics improved significantly as γ-PGA concentration increased compared to control samples.Adding γ-PGA 4 % reduced the carbonyl content from 4.20 to 3.00 nmol/ mg protein during fluctuation-1 (F1), and from 4.15 to 2.80 nmol/ mg protein during fluctuation-2 (F2) compared to control samples. Furthermore, it increased the total sulfhydryl content from 4.15 and 4.76 to 6.19 and 6.47 mol/105 g protein during F1 and F2 and after five freeze-thaw cycles (FTC). This suggests that this concentration was more effective at controlling protein changes than other concentrations. γ-PGA generally enhanced the water-holding capacity by preventing protein denaturation and limiting ice crystal recrystallization. As a result, microstructure stability was evident, texture degradation was avoided, and the crayfish's color was preserved.

Bilayer coatings for extension of the shelf life of fish fillets: Incorporating seaweed sulfated polysaccharides in chitosan-alginate LbL structures

The aim of this study was to develop a new active coating of layer-by-layer (LbL) structure composed of alginate (as polyanions) and chitosan (as a polycation) containing sulfated polysaccharide (fucoidan) from Sargassum angustifolium, to protect rainbow trout fillets during refrigerated storage. Chitosan and alginate do not combine with each other as a homogeneous solution, so they are suitable for multilayer coatings. The results demonstrated that coating samples with chitosan and fucoidan significantly improved the quality of fish fillets and extended their shelf life from 6 to 16 days. The chemical values (TBARS and TVB-N) and bacterial growth (total viable count (TVC), total psychrophilic count (PTC), and lactic acid bacteria (LAB)) indicated lower levels in the LbL coating samples containing fucoidan compared to the alginate and control samples. Among the different coating samples, the LbL coating with fucoidan (AChF1) exhibited lower weight loss, improved chromaticity (L*, a*, and b*), and minimal changes in mechanical and sensory evaluations. Based on the findings, AChF1 was the most effective treatment for increasing the shelf life of rainbow trout fillets during refrigerated storage. Therefore, it has potential applications in the food packaging industry.

The effects of double gelatin containing chitosan nanoparticles-calcium alginate coatings on the stability of chicken breast meat

The effects of gelatin coatings (2% and 4%) containing chitosan nanoparticles (ChNPs; 1% and 2%), in combination with calcium-alginate coatings (CA; 2%), on quality attributes and shelf life of chicken breast meat were evaluated at 4°C for 12 days. The results indicated that double-active gelatin-calcium alginate coatings had significant (p < .05) effects on moisture and protein content. Incorporation of ChNPs into double gelatin-CA coatings led to significant reduction (p < .05) in TBARS, pH, and TVB-N values at the end of storage. The counts of total viable count (TVC), coliforms, yeasts, and molds were significantly (p < .05) lower in all coated samples, particularly in treated samples by 4% gelatin containing 2% ChNPs + 2% CA coatings (6.85, 6.78, and 5.91 log CFU/g, respectively, compared with 8.35, 8.76, and 7.71 log CFU/g in control) at the end of keeping time. The results of sensory attributes showed that the coated samples had higher overall acceptability scores compared with the untreated samples. A synergistic relationship between the concentrations of gelatin and ChNPs was observed in maintaining the quality characteristics of meat samples during storage. Therefore, this study aims to evaluate the performance of double gelatin coating containing ChNPs in combination with CA coating in the storage quality improvement of chicken breast meat stored for 12 days at 4 °C to develop novel and practical coatings for meat and meat products.

The Effect of a Chitosan/TiO2-Nanoparticle/ Rosmarinic Acid-Based Nanocomposite Coating on the Preservation of Refrigerated Rainbow Trout Fillets (Oncorhynchus mykiss)

The aim of this study was to determine the effect of chitosan (CH)-based nanocomposite coating applications [chitosan+TiO2 (CHT) and chitosan+TiO2+rosmarinic acid (CHTRA)] on changes in quality attributes of rainbow trout fillets during cold storage (4°C). Fish fillets were randomly divided into four groups and subjected to treatments (CH, CHT, CHTRA, and control). After treatments, the groups were packaged under a modified atmosphere (40% CO2+30% O2+30% N2) and stored at 4°C for 18 days. During cold storage, the samples were subjected to physico-chemical and microbiological analyses. During storage, CH, CHT, and CHTRA treatments showed lower aerobic mesophilic and psychrotrophic bacteria counts than the control. However, the differences between coating treatments were not significant. The highest mean pH value was determined in the control group. As the storage time increased, the thiobarbituric acid reactive substances value increased. At the end of the storage period, no significant differences were observed between the treatments, including in the control group. The total volatile basic nitrogen (TVB-N) level in the control group was above 25 mg/100 g on day 15 of storage. However, the TVB-N level in the treatment groups was below 20 mg/100 g on day 18. It was also determined that coating application×storage period interaction had a significant effect on all color parameters (p<0.01). At the end of storage, the highest CIE L* was observed in CHTRA treatment. However, the value of this treatment did not differ from that of the CH treatment.

Pomegranate Peel Powder: In Vitro Efficacy and Application to Contaminated Liquid Foods

In this study the recycling of pomegranate peel powder (PPP) was proposed. In particular, the use of powder loaded in a silk fibroin polymeric matrix to create an active pad was tested. For the sake of comparison, the powder alone was also analysed. Both powder and active pad efficacy was assessed in two different food systems, soymilk (rich in proteins), preliminarily contaminated with Pseudomonas spp. and yeasts, and apple juice (rich in carbohydrates), preliminarily contaminated with Alyciclobacillus acidoterrestris. Three different concentrations of powder alone and powder in the pad were tested (5%, 7.5% and 10% w/v) in both types of beverages. To assess a possible dependence of the efficacy on the powder granulometry, different powder sizes were preliminarily analysed on Pseudomonas spp. and yeasts using an in vitro test. PPP was effective on both Pseudomonas spp. and yeasts. No significant differences appeared among the tested granulometries and therefore in the subsequent tests powder with an average diameter of 250 µm was used. Results recorded with soymilk and apple juice were different. When applied to the soymilk, the activity of PPP in the pad was less effective than that recorded when the powder was directly added to the beverage. With the two highest powder concentrations directly added to food, more than four log cycle reductions in Pseudomonas spp. and yeast cells were recorded, compared to soymilk without any powder. Compared to the control sample, all the soymilk samples either with PPP or with the active pad showed a delayed microbial and fungal growth. When applied to apple juice, both powder and pad were effective at completely inhibiting the proliferation of A. acidoterrestris (<102 CFU/g).

Potential of nanochitosan coating combined with walnut green husk to improve the preservation of rainbow trout (Oncorhynchus mykiss) during refrigerated storage

The present study evaluated the potential of nanochitosan coating enriched with ethanol-water extract of the walnut green husk (WGHE) on spoilage and rancidity of rainbow trout (Oncorhynchus mykiss) during six-day refrigerated storage. Hence, we have considered fresh trout fillets without any treatment as control (C), immersed in 2% solution of chitosan nanoparticles (CN), combination with 1.5% and 3% WGHE with nanochitosan coating (CN + WGHE 1.5 and CN + WGHE3), for physicochemical, microbial and sensorial assays. The highest levels and total volatile nitrogen were observed after day 6 in C, while the lowest was found in CN + WGHE3 groups. Thiobarbituric acid reactive substance (TBARS) and peroxide value of untreated fillets on day 6 of the study were significantly higher than NC + WGHE3 with 0.08 mg/g and 3.27 mEq/kg, respectively. The total microbial population was: C ˃ CN ˃ CN + WGHE 1.5 > CN + WGHE3, which expresses the effect of the extract on the total microbial population. Overall, the combination of WGHE with CN increased the extract's efficiency in reducing peroxide value, TBARS, and total volatile nitrogen and delayed the pH increase, improving the overall acceptability of rainbow trout fillets stored in refrigerated conditions.

Novel Active Food Packaging Films Based on Gelatin-Sodium Alginate Containing Beetroot Peel Extract

Currently, the exploration of natural colorants from vegetal waste has gained particular attention. Furthermore, incorporation of these natural sources into biopolymers is an encouraging environmentally friendly approach to establishing active films with biological activities for food packaging. The present study developed bioactive antioxidant films based on gelatin-sodium alginate (NaAlg) incorporated with aqueous beetroot peel extract (BPE). Firstly, the effects of combining gelatin-NaAlg and BPE at 0.25, 0.5, and 1% on the mechanical, physical, antioxidant, and antibacterial properties of the films were analyzed. With increasing BPE, mechanico-physical properties and antioxidant and anti-foodborne pathogen capacities were enhanced. Likewise, when added to gelatin-NaAlg films, BPE remarkably increased the instrumental color properties. Moreover, during 14 days of storage at 4 °C, the impact of gelatin-NaAlg coating impregnated with BPE on microbial and chemical oxidation and on the sensory characteristics of beef meat samples was periodically assessed. Interestingly, by the end of the storage, BPE at 1% limited the microbial deterioration, enhanced the instrumental color, delayed chemical oxidation, and improved sensory traits. By practicing chemometrics tools (principal component analysis and heat maps), all data provided valuable information for categorizing all samples regarding microbiological and oxidative properties, sensory features, and instrumental color. Our findings revealed the ability of gelatin-NaAlg with BPE as an antioxidant to be employed as food packaging for meat preservation.

Prevention of quality characteristic decline in freeze-thawed cultured large yellow croaker (Larimichthys crocea) using flammulina velutipes polysaccharide

To investigate the cryoprotective effect of flammulina velutipes polysaccharide (FVP) on the quality characteristics in freeze-thawed cultured large yellow croaker, 0.050%, 0.075%, and 0.100% FVP was used before freezing and the quality after thawing was compared with water soaking (WS) and commercial cryoprotectant (CC) treatment. Quality attributes were comprehensively determined instrumentally and organoleptically after thawing at 4°C. Results showed that FVP effectively reduces the quality deterioration of body color and water-holding capacity, while no obvious effects were observed in texture and flavor. As for body color, both FVP and CC treatment could maintain the b* value to a large extent. Among them, 0.075% FVP shows the highest value in two sample points, with 55.2% and 21.0% increases seen in the values in WS. FVP-dose-dependent trends were found in water-holding capacity, where a reduction of 28.26% and 14.38% in thawing loss and cooking loss was observed in the 0.100% FVP group. Low-field nuclear magnetic resonance (LF-NMR) also revealed that immobilized water and free water were more tightly retained in the muscle tissue with FVP addition. The results of the sensory evaluation are essentially in line with the above observations. These findings indicate that FVP has the potential to partially replace commercial cryoprotectants in aquatic products during frozen storage.

Preparation of chitosan grafted caffeic acid coating and its effect on pompano (Trachinotus ovatus) preservation

BACKGROUND

The present study aimed to investigate the preservative effect of chitosan-caffeic acid grafts coating (CS-g-CA) on the quality and microbial characteristics of pompano (Trachinotus ovatus) during iced storage. CS-g-CA was prepared by a 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydro/N-hydroxysuccinimide coupling reaction. The grafting of CS-g-CA was confirmed by UV-visible and Fourier-transform infrared spectra. Samples were treated with distilled water (control), chitosan (CS), caffeic acid (CA) and CS-g-CA for 10 min, respectively. Microbiological [total viable count (TVC), H₂ S-producing bacteria count, Pseudomonas bacteria count], physicochemical indicators [water holding capacity (WHC), cooking loss, pH, total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), texture profile analysis, free amino acids] and sensory evaluation were investigated during ice storage at 4 °C for up to 27 days.

RESULTS

The results showed that the antioxidant and antibacterial activities of CS could be improved by grafting CA onto CS. CS-g-CA coating could greatly slow down the speed of water loss and maintain WHC. Furthermore, CS-g-CA coating showed superior antibacterial activities by inhibiting the growth of TVC, delayed the decline of flavor amino acids and reduced sensory change. In addition, CS-g-CA coating reduced lipid oxidation and protein degradation as indicated by the decrease in TBA and TVB-N, possibly as a result of the addition of CA into CS membrane significantly improving the antioxidant activity of CS.

CONCLUSION

Compared with the control group, CS-g-CA coating had the optimal effect and could enhance the shelf-life of Trachinotus ovatus for at least another 9 days. © 2021 Society of Chemical Industry.

Effects of Chitosan-Grafted-Phenolic Acid Coating on Quality and Microbiota Composition of Vacuum-Packaged Sea Bass (Lateolabrax japonicus) Fillets during Chilled Storage

ABSTRACT

The aim of this research was to experimentally assess the effect of chitosan (CS)-grafted phenolic acid (CS-g-PA) derivatives on the quality and microbiota composition of vacuum-packaged sea bass (Lateolabrax japonicus). Samples were treated by deionized water (CK), 1% CS, 1% CS-g-PA copolymer, and 1% CS-grafted gallic acid (CS-g-GA) copolymer for 10 min and combined with vacuum packaging stored at 4°C to analyze the microbiological and physicochemical indicators; they were also combined with 16s RNA high-throughput sequencing to explore the effects of CS derivatives on quality and microbial composition. The results showed that the treatment of CS-g-GA and CS-g-PA could retard the increase of pH, total volatile basic nitrogen, and the K value. The degradation of ATP-related compounds, production of biogenic amines, and growth of spoilage bacteria were inhibited by CS-g-GA and CS-g-PA. Moreover, CS-g-GA and CS-g-PA performed better in the inhibition of lipid oxidation by the analysis of thiobarbituric acid reactive substances and relative fluorescence intensity. According to the results of high-throughput sequencing, the diversity of microbial composition in all groups was decreased significantly during chilled storage, especially in the CK group. The predominant microorganism was Acinetobacter in the middle period of storage, while Pseudomonas and Shewanella became predominant at the end of storage. The treatment of CS-g-GA and CS-g-PA had significant effects inhibiting the growth of Shewanella during storage. On the basis of the analysis of the microorganism and physicochemical quality, compared with the CK group, CS-g-GA and CS-g-PA can maintain the good quality of sea bass fillets and prolong the shelf life for another 12 days.

HIGHLIGHTS

The role of trifunctional cryoprotectants in the frozen storage of aquatic foods: Recent developments and future recommendations

Freeze-induced changes including protein denaturation, ice crystals formation and lipid oxidation are mainly responsible for the quality deterioration persistent in aquatic foods. Here, for the first time, the cryoprotectants with trifunctional properties have been suggested for aquatic food cryopreservation and have exhibited exceptional cryoprotective abilities. In this study, in-depth discussion of protein denaturation, ice crystal formation and lipid oxidation is added in order to understand their mechanism, emphasizing on the necessity and use of trifunctional cryoprotectants in aquatic foods during frozen storage. Trifunctional cryoprotectants have strong abilities to prevent the formation of malondihaldehyde and aldehydes resulting from lipid oxidation, which further interact with proteins, subsequently lead to protein denaturation. Besides these all cryoprotective properties, ice crystal binding abilities distinguish trifunctional cryoprotectants from conventional cryoprotectants. Moreover, this study added with recent advances in cryoprotectants including antifreeze proteins and protein hydrolysates with their role in retarded freeze-induced changes. This study concluded that trifunctional cryoprotectants are effective owing to their hydrophilic amino acid chains, radical scavenging, water entrapping abilities, as well as the hydroxyl groups, which interact at the functional sites of protein molecules. Furthermore, polysaccharides and protein hydrolysates are the potential ingredients with trifunctional cryoproperties. However, more scientific research is required for material optimization to attain the desired level of cryoprotection.

Effect of Chitosan Coating Incorporated with Artemisia fragrans Essential Oil on Fresh Chicken Meat during Refrigerated Storage

The present study was conducted to assess the impact of chitosan coating (1%) containing Artemisia fragrans essential oil (500, 1000, and 1500 ppm) as antioxidant and antimicrobial agent on the quality properties and shelf life of chicken fillets during refrigerated storage. After packaging meat samples, physicochemical, microbiological, and organoleptic attributes were evaluated at 0, 3, 6, 9, and 12 days at 4 °C. The results revealed that applied chitosan (CH) coating in combination with Artemisia fragrans essential oils (AFEOs) had no significant (p < 0.05) effects on proximate composition among treatments. The results showed that the incorporation of AFEOs into CH coating significantly reduced (p < 0.05) pH, thiobarbituric acid reactive substances (TBARS), and total volatile base nitrogen (TVB-N), especially for 1% CH coating + 1500 ppm AFEOs, with values at the end of storage of 5.58, 1.61, and 2.53, respectively. The coated samples also displayed higher phenolic compounds than those obtained by uncoated samples. Coated chicken meat had, significantly (p < 0.05), the highest inhibitory effects against microbial growth. The counts of TVC (total viable counts), coliforms, molds, and yeasts were significantly lower (p < 0.05) in 1% CH coating + 1500 ppm AFEOs fillets (5.32, 3.87, and 4.27 Log CFU/g, respectively) at day 12. Organoleptic attributes of coated samples also showed the highest overall acceptability scores than uncoated ones. Therefore, the incorporation of AFEOs into CH coating could be effectively used for improving stability and shelf life of chicken fillets during refrigerated storage.

Effects of dietary pomegranate peel meal on the growth performance, blood indices, and innate immune response of rainbow trout (Oncorhynchus mykiss)

The present study aimed at evaluating the influences of pomegranate peel meal on the growth performance, hematology, and blood biochemistry of rainbow trout. Fish were fed 5 varying levels of pomegranate peel meal (0%, 1%, 2 %, 3%, and 4%) for 60 days. The obtained results showed that weight gain was significantly higher in fish fed at the rate of 1% than the other groups, while specific growth rate (SGR) was significantly increased in fish fed 1% and followed by the ration of 2% (P<0.05). SGR of fish fed at the rate of 4% revealed the lowest value among the groups (P<0.05). However, feed conversion ratio displayed the lowest values in fish fed at the rate of 1% or 2%, while the highest value was observed in fish fed at the rate of 4% (P<0.05). The survival rate was increased by the rate of 1% in relation to the control without differences with the other groups (P<0.05). Red blood cells were significantly higher in fish fed at the rate of 0%, 1%, and 2% than fish fed at the rate of 3% and 4%. Hematocrit and hemoglobin levels were increased by feeding pomegranate meal at the rate of 1% compared to the other groups, while fish fed the control diet displayed higher Hb and HCT levels than fish fed at the rate of 2%, 3%, and 4% (P<0.05). White blood cells displayed significant differences among the groups and increased by increasing the level of pomegranate meal in the diet. The blood total protein was decreased in fish fed 2%, 3%, and 4% compared to fish fed at the rate of 0% and 1% of pomegranate meal. The glucose value displayed the highest level in fish fed at the rate of 3% of pomegranate meal compared to the other groups. The triglycerides were reduced by pomegranate meal at the rate of 2% than 3% and 4% without differences with the control and 1%. The blood total cholesterol was reduced in fish fed at the rate of 1% of pomegranate meal compared to the other groups (P<0.05). The blood IgM and complement components (C3 and C4) were increased by increasing the supplementation level of pomegranate meal with the highest value in fish fed at the rate of 3% (P<0.05). In conclusion, dietary pomegranate meal at the rate of 1% is recommended for enhancing the growth rate and health status of rainbow trout.

Food Applications and Potential Health Benefits of Pomegranate and its Derivatives

Pomegranate (Punica granatum L.) is an ancient fruit that is particularly cultivated in west Asia, though it is also cultivated in the Mediterranean region and other parts of the world. Since ancient years, its consumption has been associated with numerous health benefits. In recent years, several in vitro and in vivo studies have revealed its beneficial physiological activities, especially its antioxidative, antimicrobial and anti-inflammatory properties. Furthermore, human-based studies have shown promising results and have indicated pomegranate potential as a protective agent of several diseases. Following that trend and the food industry's demand for antioxidants and antimicrobials from natural sources, the application of pomegranate and its extracts (mainly as antioxidants and antimicrobials), has been studied extensively in different types of food products with satisfactory results. This review aims to present all the recent studies and trends in the applications of pomegranate in the food industry and how these trends have affected product's physicochemical characteristics and shelf-life. In addition, recent in vitro and in vivo studies are presented in order to reveal pomegranate's potential in the treatment of several diseases.

Vegetable Additives in Food Packaging Polymeric Materials

Plants are the most abundant bioresources, providing valuable materials that can be used as additives in polymeric materials, such as lignocellulosic fibers, nano-cellulose, or lignin, as well as plant extracts containing bioactive phenolic and flavonoid compounds used in the healthcare, pharmaceutical, cosmetic, and nutraceutical industries. The incorporation of additives into polymeric materials improves their properties to make them suitable for multiple applications. Efforts are made to incorporate into the raw polymers various natural biobased and biodegradable additives with a low environmental fingerprint, such as by-products, biomass, plant extracts, etc. In this review we will illustrate in the first part recent examples of lignocellulosic materials, lignin, and nano-cellulose as reinforcements or fillers in various polymer matrices and in the second part various applications of plant extracts as active ingredients in food packaging materials based on polysaccharide matrices (chitosan/starch/alginate).

Shelf-Life Enhancement in Fresh and Frozen Rainbow Trout Fillets by the Employment of a Novel Active Coating Design

The goal of this study was to determine the effect of incorporating ethanolic Prosopis farcta extract (PFE, 0 and 0.5%) and curcumin nanoparticles (CCM, 0, 0.1 and 0.2%) into sodium alginate (SA) coating on shelf-life of refrigerated and frozen rainbow trout fillets during storage lasting for 12 days and 6 months, respectively. Antioxidant and antibacterial properties of designated coatings were examined using 2, 2-diphenyl-1-picrylhydrazyl hydrate free radical scavenging activity and broth microdilution methods, respectively. The highest antioxidant and antibacterial activities were found in CCM 0.2% + PFE 0.5% and CCM 0.1% + PFE 0.5%. The CCM 0.2% + PFE 0.5% and CCM 0.1% + PFE 0.5% treatments could significantly extend the shelf-life of fresh trout fillets for 12 days during refrigerated storage evidenced by the 3.6 to 4.3 and 3 to 3.7 log CFU/g decrease in the microbial population in comparison with the untreated group, respectively. At the end of refrigerated storage time, the chemical change in all treated fillets was significantly lower than the untreated group (P < 0.05). The treatments of frozen trout fillets with SA + different concentrations of PFE and CCM resulted in better microbial and chemical properties than of the untreated group at the end of storage period (P < 0.05). PRACTICAL APPLICATION: Antimicrobial edible coatings from natural renewable resources have been found to be very useful in the food preservation field owing to the increasing consumer interest for the improvement of shelf-life property and appearance of fresh foodstuffs. Rainbow trout fillets without chemical preservatives have a limited shelf-life due to its biological properties. This study indicates the possibility of application of sodium alginate coatings containing Prosopis farcta extract and curcumin nanoparticles to increase shelf-life and maintain the quality of refrigerated trout fillets.

Review on Natural Preservatives for Extending Fish Shelf Life

Fish is extremely perishable as a result of rapid microbial growth naturally present in fish or from contamination. Synthetic preservatives are widely used in fish storage to extend shelf life and maintain quality and safety. However, consumer preferences for natural preservatives and concerns about the safety of synthetic preservatives have prompted the food industry to search natural preservatives. Natural preservatives from microorganisms, plants, and animals have been shown potential in replacing the chemical antimicrobials. Bacteriocins and organic acids from bacteria showed good antimicrobial activities against spoilage bacteria. Plant-derived antimicrobials could prolong fish shelf life and decrease lipid oxidation. Animal-derived antimicrobials also have good antimicrobial activities; however, their allergen risk should be paid attention. Moreover, some algae and mushroom species can also provide a potential source of new natural preservatives. Obviously, the natural preservatives could perform better in fish storage by combining with other hurdles such as non-thermal sterilization processing, modified atmosphere packaging, edible films and coatings.

Chitosan coatings incorporated with propolis extract and Zataria multiflora Boiss oil for active packaging of chicken breast meat

The impact of dipping in combination of propolis extract (PE) and chitosan (CH) coating enriched with Zataria multiflora essential oil (ZEO) on chemical, microbial and organoleptic properties of poultry meat was determined at 4 °C. GC-MS analysis showed that the most components of PE were Dihydrochrysin (9.69%) and b- Pinostrobin (7.41%). The results of mesophilic total viable plate counts (TVC), lactic acid bacteria (LAB), Psychotropic bacteria and Pseudomonas spp. showed detectably lower (p < 0.05) microbial count in CH-PE 1%-Z 0.5% and CH-PE 1%-Z 1% samples at the last day of storage. The results of chemical characteristics (pH, total volatile base nitrogen (TVB-N), 2-thiobarbituric acid reactive substances (TBARS)) in all treated samples compared with the control, revealed that there is a synergistic effect between CH, PE and ZEO. In the sensorial assessment, treatments containing 1% PE- 0.5% ZEO and 1% PE- 1% ZEO were mostly acceptable by the sensory analyst. These results offer a successful approach that chitosan coating enriched with combination of ZEO and PE can be an improving method to reducing deterioration of fresh packed chicken meat.

Recent progress in biomedical applications of chitosan and its nanocomposites in aquaculture: A review

Chitosan nanoparticles (CSNPs) are the nanostructures of chitosan biopolymer which is derived from chitin polysaccharide, the main component of crustacean shells. Chitosan is a biocompatible, nontoxic and biodegradable polymer soluble in acidic solutions and easily excreted from kidneys. It is widely used in medical and pharmaceutical applications including artificial matrices for tissue engineering, drug transport, targeted drug delivery and protein or gene delivery. The antimicrobial activities of chitosan and CSNPS against different bacterial, fungal and viral pathogens made them valuable for several biological applications including food preservation purposes. In addition, they have immunomodulatory effects on fish and crustaceans providing direct positive impact on aquaculture and fish farming industry. Sustained release of some bioactive ingredients such as hormones, vitamins, nutrients and antioxidants has improved the biological activities of fish. Furthermore, CSNPs have recently been employed to diagnose fish diseases. In this review, we present the medical and biological applications of chitosan and CSNPs on aquatics to provide an update on recent advances and the potential for further advanced applications for aquaculture in the future.

Impact of glazing based on chitosan-gelatin incorporated with Persian lime (Citrus latifolia) peel essential oil on quality of rainbow trout fillets stored at superchilled condition

In this research, a new ice-glazing based on chitosan-gelatin (Ch-Gl) incorporated with Persian lime peel essential oil (LEO), and superchilled storage was established to assess the microbial, physicochemical, and sensory quality of rainbow trout fillets. The fillets were immersed in distilled water (control), Ch-Gl, Ch-Gl + 1% LEO, and Ch-Gl + 2% LEO to form glazing layer on the surface, then stored at -1.4 °C for 30 days. All treatments delayed the growth of total mesophilic bacteria, total psychrotrophic bacteria, Enterobacteriaceae, and lactic acid bacteria compared to control during the storage period. The treatments also retarded the increase in the contents of total volatile nitrogen, conjugated dienes, thiobarbituric acid reactive substances, protein carbonyls, pH, and electric conductivity during storage. The freshness indexes i.e. K and F_r values were improved in treated groups compared to control group. The combined treatments (Ch-Gl + 1% or 2% LEO) were more effective than Ch-Gl alone to inhibit the microbial growth, retard the physicochemical deterioration, and improve freshness indexes in the fillets. It can be concluded that ice-glazing based on Ch-Gl incorporated with LEO, and superchilled storage is effective to enhance the quality and shelf-life of rainbow trout fillets.

Chitosan-Starch Films with Natural Extracts: Physical, Chemical, Morphological and Thermal Properties

The aim of this study is to analyze the properties of a series of polysaccharide composite films, such as apparent density, color, the presence of functional groups, morphology, and thermal stability, as well as the correlation between them and their antimicrobial and optical properties. Natural antioxidants such as anthocyanins (from cranberry; blueberry and pomegranate); betalains (from beetroot and pitaya); resveratrol (from grape); and thymol and carvacrol (from oregano) were added to the films. Few changes in the position and intensity of the FTIR spectra bands were observed despite the low content of extract added to the films. Due to this fact, the antioxidants were extracted and identified by spectroscopic analysis; and they were also quantified using the Folin-Denis method and a gallic acid calibration curve, which confirmed the presence of natural antioxidants in the films. According to the SEM analysis, the presence of natural antioxidants has no influence on the film morphology because the stretch marks and white points that were observed were related to starch presence. On the other hand, the TGA analysis showed that the type of extract influences the total weight loss. The overall interpretation of the results suggests that the use of natural antioxidants as additives for chitosan-starch film preparation has a prominent impact on most of the critical properties that are decisive in making them suitable for food-packing applications.